Exhaust Tips....Resonators?

The least expensive thing to do is install a cross over between the two sides just behind the torsion bar cross member. Kits are available from Jegs and Summit.

When my Barracuda had the \6 I had dual exhaust installed (6 into 2 headers) with glass paks. Way to loud and the sound quality was not good a WOT. Purchased an H-pipe kit for short change from Summit. It made all the difference in the world in the sound. Cut the volume way down, got rid of most of the interior resonance and smoothed out the WOT noise to the point I was getting compliments on how it sounded.

FWIW, I have 2.5" pipes, 50 series flowmasters and an x-pipe crossover with the 360 that's in there now and it's even quieter with even less interior resonance than with the \6 glass pak combo.